Electrolyte health management for redox flow battery

Patent metadata

Field	Value
Publication number	US-2020161685-A1
Application number	US-201916684429-A
Country	US
Kind code	A1
Filing date	Nov 14, 2019
Priority date	Nov 20, 2018
Publication date	May 21, 2020
Grant date	—

Abstract

Methods and systems are provided for a rebalancing reactor of a flow battery system. In one example, a pH of a battery electrolyte may be maintained by the rebalancing reactor by applying a negative potential to a catalyst bed of the rebalancing reactor. A performance of the rebalancing reactor may further be maintained by treating the catalyst bed with deionized water.

First claim

1 . A method for treating a rebalancing reactor of a flow battery comprising;
flowing an electrolyte of the flow battery and hydrogen gas generated in the flow battery to the rebalancing reactor; applying a negative potential to a catalyst bed of the rebalancing reactor while flowing the electrolyte; detecting a decrease in a ferric iron reduction rate at the catalyst bed below a threshold rate; flowing deionized water instead of electrolyte across the catalyst bed in response to the decrease in the ferric iron reduction rate; and indicating, after a threshold interval of rebalancing reactor operating time elapses, a request for soaking of the catalyst bed in deionized water.

2 . The method of claim 1 , wherein applying the negative potential to the catalyst bed includes coupling a conductive wire to the catalyst bed, and transmitting a voltage from an electric device to the catalyst bed.

3 . The method of claim 1 , wherein applying the negative potential to the catalyst bed includes generating a negative charge on the catalyst bed, the negative charge repelling electrolyte anions from the catalyst bed, and maintaining the negative potential above a threshold potential during operation of the rebalancing reactor.

4 . The method of claim 3 , wherein generating the negative charge on the catalyst bed includes maintaining the negative charge on the catalyst bed while the redox flow battery is charging.

5 . The method of claim 1 , wherein flowing the deionized water across the catalyst bed includes halting flow of electrolyte and hydrogen gas to the rebalancing reactor and wherein halting flow of electrolyte to the rebalancing reactor includes closing a first set of valves controlling flow between the battery cell and the rebalancing reactor.

6 . The method of claim 5 , wherein flowing deionized water across the catalyst bed includes opening a second set of valves controlling flow between a deionized water reservoir and the rebalancing reactor, the deionized water reservoir fluidly coupled to the rebalancing reactor.

7 . The method of claim 5 , wherein soaking the catalyst bed includes halting flow of electrolyte to the rebalancing reactor by closing the first set of valves, removing the catalyst bed from the rebalancing reactor, and submerging the catalyst bed in heated deionized water for a predetermined period of time in a predetermined volume of deionized water.

8 . The method of claim 1 , wherein flowing deionized water across the catalyst bed flushes the catalyst bed and wherein the flushing terminates when the deionized water emerging from the rebalancing reactor reaches a target resistivity.

9 . A redox flow battery system, comprising;
an electrolyte circulating through a cell of the redox flow battery and hydrogen gas stored in electrolyte chambers of the redox flow battery, both the electrolyte and hydrogen gas flowed to a rebalancing reactor coupled to the cell; a negative potential applied to the catalyst bed during charging of the redox flow battery; a controller, configured with computer readable instructions stored on non-transitory memory, the instructions executable by the controller to:
apply a negative potential to the catalyst bed during charging of the redox flow battery;
flush the catalyst bed with deionized water upon detection of the rate of ferric iron reduction at the rebalancing reactor falling below a second threshold; and
indicate a request for soaking of the catalyst bed in deionized water when an interval of operating time of the redox flow battery is elapsed.

10 . The redox flow battery system claim 9 , wherein the electrolyte includes ferric and ferrous iron complexes, non-redox active salts, and an acid.

11 . The redox flow battery system of claim 9 , where the hydrogen gas is generated at a negative electrode of the cell in a process that consumes protons from the electrolyte.

12 . The redox flow battery system of claim 9 , wherein the catalyst bed of the rebalancing reactor has a jelly roll structure.

13 . The redox flow battery system of claim 9 , wherein the negative potential applied to the catalyst bed is configured to generate a negative charge at the catalyst bed and wherein the negative potential is applied continuously during operation of the redox flow battery.

14 . The redox flow battery system of claim 9 , wherein the catalyst bed is flushed with deionized water while housed in the rebalancing reactor when deionized water is flowed through the rebalancing reactor.

15 . The redox flow battery system of claim 9 , wherein the catalyst is soaked when the redox flow battery system is deactivated and the catalyst is removed from the rebalancing reactor.

16 . A method for treating a rebalancing reactor of a flow battery, comprising:
flowing an electrolyte of the flow battery and hydrogen gas generated in the flow battery to the rebalancing reactor; detecting a decrease in an iron reduction rate of the rebalancing reactor; and responsive to the decrease in iron reduction rate, halting flow of electrolyte and hydrogen gas to the rebalancing reactor and flowing deionized water through the rebalancing reactor.

17 . The method of claim 16 , wherein detecting the decrease in the iron reduction rate of the rebalancing reactor includes measuring the iron reduction rate to be below a threshold rate that decreases a performance of the rebalancing reactor.

18 . The method of claim 16 , wherein flowing deionized water includes directing deionized water from a reservoir to the rebalancing reactor.

19 . The method of claim 16 , further comprising maintaining a negative charge on a catalyst bed of the rebalancing reactor during operation of the flow battery.

20 . The method of claim 16 , wherein flowing the electrolyte to the rebalancing reactor includes delivering the electrolyte from a battery cell of the redox flow battery to the rebalancing reactor and wherein the rebalancing reactor is configured to restore a pH and ferrous iron concentration of the electrolyte.

Assignees

• Ess Technology Inc

Inventors

• Song Yang
• Mcdonald Timothy J
• Behr Alexandria

Classifications

• H01M8/188 Primary

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title

• H01M8/04186

  of liquid-charged or electrolyte-charged reactants · CPC title

• H01M8/0693 Primary

  Treatment of the electrolyte residue, e.g. reconcentrating · CPC title

• H01M8/0444

  Concentration; Density (H01M8/04492 takes precedence) · CPC title